Internal combustion engine



July 4, 1933. M, WOOLLSON 1,916,292

INTERNAL COMBUSTIOVN ENGINE Filed Dec. 1l, 1925 Patented July 4, 1933UNITED STATES PATENT OFFICE LIONEL M. WOOLSON, OF DETROIT, MICHIGAN,ASSIGNOR T PACKARD MOTOR CAB COMPANY, 0F DETROIT, MICHIGAN, A.CORPORATION OF MICHIGAN INTERNAL COMBUSTION ENGINE Application ledDecember 11, 1925. Serial No. 74,722.

This invention relates to internal Combustion engines and particularlyto large high speed engines such as are used in the propulsion ofaircraft. In such engines reliability, compactncss and a low ratio ofweight to power developed are prime requisites, but because of the lightconstruction and the high power developed, and also by reason of thehigh speeds employed, they are frequently subject to severe vibrationwhich tends .to weaken the engine and adversely affect its reliability.

Engines of this nature are usually of the i V type, having a singlecrankshaft mounted in bearings which are supported on webs cast integralwith the crankcase and transversely disposed therein. In the interest oflightness it has become the practice to cast the crankcase from aluminumand to form the bearing caps of duraluniin or similar material, thesecaps being carried by studs which are screwed into the webs of thecrankcase.V It has been found that in structures of this nature theheavy stresses caused by the explosion load are concentrated on thethreads in the stud holes of the crankcase webs, and these stresses,when rapidly reversed at high engine speeds, tend to cause the formationof minute cracks in the crankcase adjacent the stud holes, which rapidlyspread and may cause the complete failure of the engine. It hasheretofore been proposed to carry the bearing caps of internalcombustion engines on bolts verticallv arranged in the crankcase andpassing therethrough, but in the type of engine under discussion thecylinders are usually so closely spaced in the interest of compactnessthat such construction is impractical, there being no room for the headsof such bolts. 1

One of the objects of the present invention is to provide an engine ofthe character designated in which the loads on the crankcase and itswebs, caused by the explosions in the engine cylinders, shall be takenby members in direct tension, and the members beingarranged parallel tothe axes of the cylinders.

Another object of the invention is to provide such an engine having acrankcase of aluminum or similar material, in which the loads imposedupon such crankcase shall not be communicated thereto through threadscut in the aluminum itself.

Another object of the invention is to provide. an internal combustionengine with a bearing cap support -in which the bending moment is aminimum.

A further object of the invention is to provide such an engine with abearing cap support which is carried by bolts or other tension membersin such a manner that localization of stresses in the threaded portionof the bolts is impossible and which shall yield in elongation ratherthan by fracture.

Other objects of the invention will appear from the followingdescription taken in connection with the drawing, which forms a part ofthis specification and in which:

Fig. 1 is a view in vertical longitudinal section through a portion ofan internal combustion engine, taken substantially on the line 1-1 ofFig. 2;

Fig. 2 is a transverse vertical section through a portion of theinternal combustion engine shown in Fig. 1 and substantially on thelines 2 2 of Figs. 1 and 3, showing the application of the inventionthereto;

Fig. 3 is a detail section taken substantially on the line 3-3 of Fig.2, and

Fig. 4 is a detail section showing the pre` ferred arrangement at oneend of the engine crankcase, substantially on the lines 4.-4 of Figs. 1and 3.

Referring to the drawing, at 10 is shown a portion of an internalcombustion engine of the well known V type, having a crankcase 11 onwhich are mounted inclined banks of cylinders 12 and 13, in a mannerwell known in the art to which this invention relates. The crankcase 11is provided with suitable feet or lugs 14 by means of which the enginemay be mounted in the vehicle which it is intended to propel and it isalso provided with suitable internal webs l5, disposed transversely ofthe crankcase and preferably cast integral therewith. The webs 15 areprovided with suitable openings 16 to lessen their weight and havedownwardly disposed faces 17 inclined to the longitudinal median planeof the engine. These faces form, in effect, an inverted V, the sides ofwhich are normal to the axes of the cylinders 12 and 13 respectively.The central portion of the webs 15, approximately at the apex of this V,is provided with a cutout portion 18 of semi-circular contour, adaptedfor the reception of the upper half of a crankshaft bearing 19. Thebottom of the crankcase is covered with a removable oil pan 20, forminga sump for the lubricating system of the engine.

In the bearing 19 is journaled the engme crankshaft 21 having cranks 22which are adapted for connection by connecting rods 23 to suitablepistons (not shown), disposed in the cylinders 12 and 13 in the wellknown manner. Each of the cranks 22 is adapted for operation by two ofthe connecting rods `23, one of which is disposed in a cylinder of eachof the cylinder banks, in the well known manner, and which maybe of theforked construction shown, or connected to the crank pin in any vothersuitable manner desired.

Below each of the webs 15 is arranged a bearing cap member 24 which maybe formed of forged duralumin, or of any other suitable material, andwhich is provided with upwardly disposed inclined faces 25, arranged inthe general form of an inverted V to coact with the downwardly disposedfaces 17 of the crankcase web 15. It will be observed that by reason ofthe shape of the cap member 24 it is wider at its upper portion adjacentthe faces 25 than itis at its lower portion and it is provided at thecenter of its upper portion, approximately at the apex of the V with acutout portion 26 of semi-circular contour adapted to complement theportion 18 and receive the lower half of the crankshaft bearing 19.

The crankcase web 15, and its co-operating cap member 24 are eachprovided with oppositely disposed aligned holes 27 in which tensionmembers 28 are disposed. These members 28 have a main body portion of adiameter to fit the holes 27 and extending through the cap 24 into thewebs 15, thus serving as dowels to positon the cap member againstlongitudinal and lateral displacement with respect to the web 15. Theyare also provided with a reduced neck portion 29 of a diameter less thanthat of the hole 27 and are threaded at their upper ends, beyond theneck portion 29, on a portion having a diameter substantially equal tothe main body portion of the bolt. By means of this construction thelocalization of stresses in the threaded portion of the bolt 28 isavoided, the neck portion 29 being adapted to yield in elongation beforethe bolt will break or the threads thereof be stripped. The lower endsof these bolts are provided with suitable heads 31 adapted to bearagainst washers 32 which are seated on small inclined shoulders or faces33 formed at the lower end of the cap member 24. The upper ends of thebolts 29 extend through the' crankcase 15 and are fitted with nuts 34adapted to coact with the threaded portion 30 thereof and to seat on theouter face of the crankcase. By means of these nuts tension can beplaced on the bolts in such a manner as to draw the co-operating faces17 and 25 of the web and the cap member respectively tightly intoengagement and thereby clamp the crankshaft bearing 19 firmly therebetween. The nuts 34 may be provided with any suitable locking meanssuch as the lock nuts 36 if desired.

It will be observed that by reason of the disposal of the webs' 15between adjacent cylinders in either bank, the ends of the bolts 28project through the upper face of the crankcase 11 at points betweensuch cylinders, as clearly shown in Fig. 3, so that there is plenty ofroom for the application and removal of the nuts 34. For this purpose,and to provide a good square seat, the base flanges 37 of the cylinders12 and 13 comprising the cylinder banks, which are preferably secured tothe -crankcase 11 by means of studs 38, may be cut away adjacent thenuts 34 as indicated at 39 in Fig. 3. It will likewise be noticed thatthe arrangement of the bearing ca 24 and its support bolts 28 in no Wiseinte eres with the lubrication of the bearing 19, which 1s preferablyeffected through suitable ducts 41 formed in the flanges 15 andcommunicating with a conduit 42 disposed longitudinally of the crankcase11.

In Figs. 1 and 4 are illustrated a modified arrangement of the bearingsupport above described, which is especially adapted for use at thereduced end 43 of the crankcase 11, which is adapted to house a thrustbearing 44 at either or both ends of the crankshaft 21. In thisarrangement a shoulder 45 is formed on the crankcase web 46, which is ofless size than the webs 15, and this shoulder 45 is adapted to form aseat for a nut 47 on the end of a tension member 48. The bolt 48 isdisposed in the web 46 and its co-operating bearing cap 49 in a mannersimilar to that which the bolt 28 is disposed in the web 15 and itsco-operating cap 24.

It will be readily seen that the bearing cap support 24 forms a beammember carried at lts outer ends by the bolts 28 and loaded intermediateits ends by the crankshaft 21, and that this beam is wider at its upperthan at its lower portion, the supports being located almost directlyunder the load. In this way the bending moments on the member 24 arereduced to a minimum and the stiffness of this part is greatlyincreased.

It will also be apparent that the loads caused by the firing of thecylinders 12 and 13 are taken in almost direct tension on the bolts 28,the loads shifting from one bolt to the other as the cylinders firealternately in the respective c linder banks.

It will be un erstood that various forms of the invention other thanthose described may be used without departing from the spirit or scopeof the invention.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent, is:

1. The combination in an internal combustion engine having a crankcaseand banks of cylinders thereon of Webs arranged transversely of theorankcase, a cap member in the vertical plane of each web, a bearingsupported between each web and its cap member and oppositely inclinedbolts passing through each cap member and web parallel to the respectivecylinder banks, said bolts having LIONEL M. WOOLSON.

